1. Technical Field
This invention relates generally to a device for dilating an opening through a wall of a patient's air passageway. More particularly, the invention relates to a dilational device having a balloon retention mechanism for maintaining a position of the balloon across the air passageway wall during dilation of the passageway.
2. Background Information
The restoration of an adequate air passageway is the first critical step in maintaining the ability of a seriously ill or injured patient to breathe, or in performing resuscitation on a patient unable to breathe. Endotracheal intubation (the placement of a tube through the nostrils or mouth and into the trachea itself) is generally considered the preferred method for establishing an air passageway when the trachea, nostrils and/or mouth are free of obstruction. When an obstruction is present, however, endotracheal intubation is often not possible, and some other passageway for airflow must be established.
The most direct way to provide an air passageway under these circumstances is to form an opening in the tracheal wall, and once formed, to maintain the opening by inserting a tracheostomy tube therethrough. Conventional tracheostomy tubes generally include an open distal aperture, and a circumferential inflatable cuff to provide a seal between the tracheal wall and the tracheostomy tube.
Several methods and devices are known for forming or enlarging an opening in a tracheal wall. Each method is subject to certain advantages and disadvantages. For example, tracheostomy and cricothyrotomy procedures have been performed by using a scalpel to make an incision in the neck. Such procedures entail a high degree of surgical skill to perform successfully, particularly since it is vital to locate and avoid unintentional severing of the blood vessels in the area. These procedures can even require the surgeon to cut through several blood vessels and ligate (tie) them to the trachea, in order to achieve an adequately large opening. The length of time needed to perform these procedures (often on the order of half an hour) is poorly suited to emergency treatment, when prompt restoration of the air passageway is critical. Moreover, the use of a scalpel to fully form an opening potentially causes undue trauma to the tissues surrounding the opening, and can result in the formation of an unduly large or oversized opening in the soft tissue of the neck.
To minimize such trauma, it has been found desirable to initially incise only a small opening, and thereafter enlarge the opening with further dilation. For example, one technique for dilating an opening includes the use of a wire guide to facilitate the introduction of a dilator into the trachea. This technique involves making a small incision with a scalpel, and inserting a needle and wire guide through the incision. The needle is removed, and a tapered, elongated, tubular dilator is positioned over the wire guide and introduced into the trachea. One drawback of this technique is that the tubular dilator must thereafter be withdrawn, and a loading dilator/tracheostomy tube combination must then be inserted over the wire guide. Even though intended to be performed in an emergency situation, the technique entails the sequential manipulation of several devices by the physician, which is time consuming and complicates the procedure.
In another procedure, an opening formed by the needle is dilated by the use of a device having a handle and a nose, the nose extending laterally from the axis of the handle. The nose has two jaws that spread apart for separating the tissue surrounding the opening, and the device is introduced into the trachea by positioning the elongated, tapered nose over the wire guide. While this type of device may offer more powerful dilation than elongated tubular dilators, a problem with this device is that the unguarded nose must be inserted into the trachea with precision, and must be manipulated at an angle to avoid perforating the posterior tracheal wall.
Another prior art technique for dilating an opening is the use of a tapered, elongated, tubular dilator, or a series of tapered dilators having increasingly larger diameters. Although such dilators are effective for forming a suitably-sized opening in the tracheal wall, each dilator presents a pointed distal end to the posterior tracheal wall when introduced into the trachea. The risk of injury to the trachea is compounded by the toughness of the tracheal membrane, which resists the introduction of medical devices. Introducing these elongated dilators typically requires the application of considerable force. Although a hydrophilic coating may be applied to the dilator to reduce the amount of force required to insert the dilator, a physician must still exert a downward force to push the dilator into the trachea, and yet avoid puncturing the posterior tracheal wall.
Prior art devices described in U.S. Pat. Nos. 5,653,230 and 7,036,510, both incorporated by reference herein, describe devices and methods for radially dilating a tracheal opening. A catheter having a polymeric inflatable balloon at the distal end of the catheter is provided. The uninflated balloon is positioned across an opening formed in the airway wall. The balloon is slowly inflated, thereby radially dilating the opening in the tracheal wall to form an ostomy of suitable size to permit insertion of a tracheostomy tube. Since these devices permit the radial enlargement of an opening, they eliminate the necessity of exerting the downward or axial push force required by many existing devices.
Although the devices described in the '230 and '510 patents are generally effective for radially dilating the opening in the tracheal wall, it is possible that the balloon may slip into or out of the trachea during inflation. Such slippage may occur, for example, as a result of inflation forces acting upon the balloon, and/or due to the resistance exerted by the tissue being dilated by the inflating balloon. When this occurs, the user generally must deflate the balloon, reposition it across the tracheal wall, and repeat the balloon inflation. Since these steps involve providing, or maintaining, an adequate airway for the patient, any additional steps that must be carried out to achieve proper positioning of the tracheostomy tube are inherently undesirable.
It would be desirable to provide a dilational device capable of radially dilating an opening in a tracheal wall, and that is structured in a manner to inhibit slippage or other undesired movement of the balloon during dilation.